Glue lap closure



Dec. 10, 1963 F. w. GREEN GLUE LAP CLOSURE 2 Sheets-Sheet 1 Filed Sept.29, 1961 INVENTOR. FRANK h- Giff/V 3,113,713 GLUE LAP CLOSURE Frank W.Green, East Longmeadow, Mass, assignor to West Virginia Pulp and PaperCompany, New York, N .Y.,. a corporation of Delaware Filed Sept. 29,1961, Sier. No. 141,828 6 Claims. (Cl. 229-51) This invention relates toa new and improved glue lap closure for paperboard cartons, boxes andother containers. More specifically it relates to a glue lap closurewith a specially shaped pattern of adhesive areas in the lapped portionproviding a tight seal for the container yet which can be easily andcleanly opened without the use of a knife or other tool of any kind.

At the outset it should be pointed out that the word glue is used hereinin the generic sense as it is often employed in the folding box andcorrugated box industries to denote any kind of suitable adhesivesubstance and is not used in the strict sense of the word which islimited .to adhesives of animal origin.

In the past many types of glue lap closures have been used. Some ofthese closures are completely glued along the full length and width ofthe lapped portions. Opening these containers at the glue lap by hand isquite difficult, if not impossible. Other glue lap closures have glueapplied in patterns of dots, or lines, or are printed with variouspatterns of glue-rejecting ink at the glue lap which prevent or resistadherence at those areas, to provide a weakened and more easily openableclosure.

In accordance with this invention, the glue is applied to the lappedportion in a special pattern of decreasing bonding area in the directionof pull, thus allowing the ease of opening to be increased and theopening speed to be accelerated as pull is exerted. A further and mostimportant advantage of the invention is the elimination of delaminatedareas which in other forms of glue lap closures may be formed in areasof the paperboard adjacent to the glue lap as a result of failure of theclosures to provide for a clean release when pulled open.

The invention is further described in the following drawings, in whichFIG. 1 is a plan view of a paperboard carton blank showing theoverlapping and underlapping portions of the glue lap closure before thecarton is formed and closed, the underlapping portion having a preferredform of glue pattern applied thereon;

FIG. 2 is a perspective view showing a paperboard carton made from theblank of FIG. 1 before the over lapping and underlapping portions of theglue lap closure are sealed together;

FIG. 3 is an enlarged fragmentary view of the gluerejecting ink patternand glue line on the underlapping portion of the glue lap closure ofFIGS. 1 and 2;

FIG. 4 is an enlarged fragmentary view of another embodiment of theunderlapping portion of the glue lap closure showing the same inkpattern but with the glue line adjusted to give stronger adhesion;

' FIG. 5 is another enlarged fragmentary view of the underlappingportion of another embodiment of glue lap closure showing a glue lineapplied over a somewhat different ink pattern;

FIG. 6 is a perspective view showing thecarton of FIG. 2 after sealing;

FIG. 7 is a perspective view of a paperboard carton with an opened gluelap closure which was sealed with glue in the form of conventionalrectangular patterns, illustrating the delamination which can occur whenthe special glue pattern of this invention is not utilized.

In FIG. 1, the paperboard carton blank is scored to provide bottom panel10, side panels 12 and 14 with side end flaps 16, '18-, 20 and 22,respectively, and end panels 24 and 25, all of which form the bottomhalfof the carton when the side end flaps and side end panels of each endare secured together.

The blank is also scored to form top panel 28, hinged to side panel 14,top end flaps 3t 32 and front flap 34, all of which constitute the tophalf of the carton. The top half of the carton is closed and sealed bygluing the top end flaps 30 and 32 to the side end flaps 24 and 26,respectively, and securing part of front flap 34 to the upper portion ofside panel 12. Front flap 34 includes pull tab 36 at the end thereoffoldably connected to the body portion of the front flap. This bodyportion of the front flap becomes overlapping portion 38 of the glue lapclosure when the carton is sealed. Pull tab 36 and overlapping portion38 each overlap a portion of side wall 12 when the carton is sealed,.theportion of side wall 12 which is covered by overlapping portion 38 beingdesig-- nated as underlapping portion 40' of the glue lap closure.

Overlapping portion 38 is scored with curvilinear perforated lines 42and 44, and top panel 28 has perforated lines 46 and 48 connecting withthe curvilinear perforated lines 42 and 44 at points 50 and 52 so as toprovide a convenient rip opening means of gaining access into the cartonfrom the top of the carton. Underlapping portion 40 has a printedpattern 54- of glue-rejecting ink, with triangular areas 56 remainingunprinted. Glue line 58,

is applied across the length of the underlapping portion 4% includingprinted portions 54 and portions of the unprinted triangles 56. Theapices of the unprinted triangles 56 preferably extend to the upper edge60 of underlapping portion 40, as shown in FIGS. 1-4, giving a somewhatneater appearance to this area of the closure after it has been openedbecause none of the printed area is as subject to delamination effects.Other embodiments of the positions of the triangles are alsocontemplated by this invention as in FIG. 5, where the triangles appearbelow the edge 60. Sometimes when glue lap closures of this embodiment(FIG. 5) are carelessly opened some very slight delamination may occurextending from the apices of the triangles of the unprinted areas intothe printed areas above resulting in a somewhat unsightly appearance.

Any type of suitable ink may be used in the printed area 54 as long asit rejects or interferes with the adhesion of the glue applied to theinked surface.

Inc, Elizabeth,

by Southern Adhesives Corporation, Richmond, Virginia,

performs very. well as a bonding agent for glue lap clo sure for cartonsmade of kraft linerboard and that the bonding power of such glue issubstantially rejected by the chlorinated rubber base specified above.The amount of glue in the unprinted triangular areas 55 may be adjustedas desired for greater or less adhesion depending upon the total areawithin the triangular area covered by glue. FIG. 4 shows the glue line58 moved down below the apices of triangular areas 56 giving a greaterglued area for the same width of glue line and thus a stronger glue lapwhen the carton is sealed.

It has been a conventional practice in the past to print the overlappingor under lapping portions of glue lap closures with glue-rejecting inkleaving unprinted areas of various shapes, such as rectangles. and thenapply a glue P 3,113,713 Ice Patented Dec; 10, 1963' An example ofsuchan 1nk 1s a chlorinated rubber base rotagravure ink 3 iine across theunprinted area'to provide areas'of adhesion. When cartons with theseglue lap closures are opened, areas adjacent to the bonded areas in thedirection of the pulling force are pulled apart or delarninated. Asshown in FIG. 7, where the unprinted areas are in the forms ofrectangles, strips of delaminated material 64 the width of therectangular unprinted areas 62 can be formed because the adhesive powerof the glue at the upper edge of rectangular area 62 is stronger thanthe internal bonding strength of the overlapping portion of thepaperboard at such points. The delarnination continues as the top isopened producing an unsightly and incompletely opened box.

The instant invention arose from the discovery that by providing theadhesive areas in the shape of triangles with the apices of thetriangles in the direction of pull, the above serious delarninationconsequences are eliminated because the areas of delamination at theglued triangular areas converges and breaks away cleanly and neatly atthe apices, or close thereto, allowing the carton to be easily, neatlyand cleanly opened. In the other embodiments as shown in FIGS. 4 and 5where the glue bonds are in the form of tapered areas which do notterminate in a point, the decrease in width of their converg ing areasstill produces a substantial decrease in the tendency to causedelamination.

It is sometimes necessary, when an increase in the strength of the gluelap closure is desired for packaging a heavier item in the carton, tomove the glue line below the apices of the unprinted triangles as shownin FIGS. 4 and 5, thus giving more glued area for the same width glueline.

The ink pattern can also be changed to provide unprinted triangular ortapered areas with broader bases so as to permit a stronger bond wherethe glue lap closure begins. It is, of course, essential to thisinvention that the bonding areas be larger nearer the pull tab andprogressively decrease as they extend away from the pull tab.

The use of a glue-rejecting ink pattern between and within the glue lapclosure of this invention is merely an expedient which permits obtainingtriangular or tapered bonding areas in the glue lap closure by thesimple and convenient procedure of applying a glue line across theprinted and unprinted area with a glue applying Wheel. It is readilyapparent of course that a printed glue-rejecting ink pattern can be doneaway with if the glue is applied initially in the form of triangles ortaperedv areas within the glue lap closure area.

It is also easily seen that the triangular or tapered glue bond areas,and the glue-rejecting ink patterns it utilized, can be applied toeither or both of the overlapping and underlapping portions of the gluelap closure.

While various embodiments of this invention have been described above,the invention should not be limited to the exact details as describedbut only by the scope of the claims set forth below.

I claim as my invention:

1. A glue lap closure for a paperboard carton which can be easily openedWithout any substantial delamination comprising:

an overlapping portion and an underlapping portion of the paperboardcarton, a pull tab foldably connected to the end of the said overlappingportion, 7

a glue bond within and between the overlapping portion and underlappingportion and adhesively securing together said portions,

said glue bond being in the form of a series of tapered areas pointingaway from the said pull tab, and

each of said tapered areas having a bottom edge nearest the pull tabwith the bottom edge of each tapered area being in substantial alignmentand with each bottom edge being the widest line through said taperedareas measured parallel to said bottom edge.

2. A glue lap closure for a paperboard carton which can be easily openedwithout any substantial delamination comprising an overlapping portionand an underlapping portion of the paperboard carton,

a pull tab foldably connected to the end of said overlapping portion,

a pattern of glue-rejecting ink printed within and between theoverlapping portion and underlapping portion leaving a series ofunprinted tapered areas pointing away from the pull tab,

a glue line within and between the overlapping portion and underlappingportion extending across the said printed pattern and the said unprintedtapered areas, whereby the said portions are adhesively secured togetherby a series of v glue bonds in the form of tapered areas pointing awayfrom the pull tab, and

each of said glue bonds in the form of tapered areas having a bottomedge nearest the pull tab with the bottom edge of each glue bond beingin substantial alignment and with each bottom edge being the widest linethrough said glue bond measured parallel to said bottom edge.

3. The glue lap closure of claim 2 in which the said' unprinted taperedareas are in the form of unprinted triangles with their apices pointingaway from the pull tab.

4. The glue lap closure of claim 3 in which the said glue line extends,across a substantial portion of said unprinted triangles including theirapices.

5. The glue lap closure of claim 4 wherein the apices of the saidunprinted triangles extend to the edge of the overlapped portionsopposite from the pull tab.

6. In a paperboard carton having a top hinged to the back of the carton,top side flaps secured to opposite sides of the carton, a glue lapclosure securing the top to the front of the carton, and perforatedlines in the top and in a portion of the glue lap closure providing atop rip open-.

ing means, and improvement in the glue lap closure to provide easyopening of the carton by hand without incurring any substantialdelarnination of areas adjacent to the glue lap closure, comprising 7 atop front flap foldably connected to the front of the top and divided bya score line into an overlapping portion and a pull tab at the endthereof, an underlapping portion of the front wall of the carton overwhich lies the overlapping portion of the said top front flap,

a pattern of glue-rejecting ink printed on the surface of saidunderlapping portion which is overlain by said overlapping portion, saidpattern leaving a series of unprinted equilateral triangular areashaving their apices pointed away from the pull tab,

a glue line on said surface of said underlapping portion extendingacross the said printed pattern and the said unprinted equilateraltriangles, whereby the said overlapping and underlapping portions of thecarton are adhesively secured together by a series of glue bonds in theform of equilateral triangles and with their apices pointing away fromthe pull tab, and

each of said glue bonds in the form of an equilateral triangle havingits bottom edge nearest the pull tab with the bottom edge of each gluebond being in substantial alignment and with each bottom edge being theWidest line through said glue bond measured parallel to said bottomedge.

References Cited in the tile of this patent UNITED STATES PATENTS2,113,927 Alfred Apr. 12, 1938 2,122,480 Lowey July 5, 1938 2,133,946Bloomer Oct. 25, 1938 2,810,507 Saunders Oct. 22, 1957

1. A GLUE LAP CLOSURE FOR A PAPERBOARD CARTON WHICH CAN BE EASILY OPENEDWITHOUT ANY SUBSTANTIAL DELAMINATION COMPRISING: AN OVERLAPPING PORTIONAND AN UNDERLAPPING PORTION OF THE PAPERBOARD CARTON, A PULL TABFOLDABLY CONNECTED TO THE END OF THE SAID OVERLAPPING PORTION, A GLUEBOND WITHIN AND BETWEEN THE OVERLAPPING PORTION AND UNDERLAPPING PORTIONAND ADHESIVELY SECURING TOGETHER SAID PORTIONS, SAID GLUE BOND BEING INTHE FORM OF A SERIES OF TAPERED AREAS POINTING AWAY FROM THE SAID PULLTAB, AND EACH OF SAID TAPERED AREAS HAVING A BOTTOM EDGE NEAREST THEPULL TAB WITH THE BOTTOM EDGE OF EACH TAPERED AREA BEING IN SUBSTANTIALALIGNMENT AND WITH EACH BOTTOM EDGE BEING THE WIDEST LINE THROUGH SAIDTAPERED AREAS MEASURED PARALLEL TO SAID BOTTOM EDGE.